U.S. Navy Aircraft History

By Tommy H. Thomason

Tuesday, November 2, 2021

A Brief History of U.S.Navy Jet Speed Brakes

One of the early discoveries of the differences between prop-pulled and jet-propelled airplanes was that the latter benefited a great deal from the availability of speed brakes. When the pilot pulled the throttle to idle on the former, the propeller pitch changed rapidly to maintain rpm and the drag increased significantly; there was no need for speed brakes (there were exceptions: dive bombers needed dive brakes to keep the speed within reason in a near-vertical dive; the Grumman F8F Bearcat had small dive-recovery flaps under the wing to more quickly pull out of high-speed dives). Jet planes slowed down with the throttle reduction but far more gradually.

The speed brake design specification was a reduction from maximum speed to a specific slower speed within a given number of seconds. Avoiding much of a pitch change with extension or retraction and minimal buffet when extended was also desired.

The U.S. Navy's first jet, the McDonnell FD-1 (subsequently FH-1) Phantom had speed brakes similar to the spoilers necessary on gliders to allow for the adjustment of the glide angle on final approach. They both increased drag and to some extent, reduced lift. They extended up and down out of the wing on a parallelogram mechanism.

North American initially fitted its FJ-1 with a similar system.

However, after one side extended and the other didn't during a flight test, causing an uncommanded roll and the pilot some concern, North American substituted speed brakes scabbed onto each side of the aft fuselage.

Note that the actuator is located in a well but the speed brake itself simply closes onto the exterior skin of the fuselage.

Vought didn't initially provide its first jet, the F6U Pirate, with speed brakes.

One was quickly added to each side of the aft fuselage:

Grumman provided two speed brakes on the belly of the F9F Panther fuselage just aft of the nose wheel well. The location was retained through the Cougar; however, the F9F-9/F11F Tiger was designed with three speed brakes, one under the nose and two under the main landing gear wheel wells.

Douglas initially configured its F3D Skyknight with three speed brakes on the aft fuselage, possibly to insure the ability of the all-weather fighter to slow down as quickly as possible behind a bogey being intercepted so as not to overrun it or worse, run into it.

Photo via Paul Bless

However, the lower dive brake was deleted for production.

McDonnell retained the FD/FH wing-mounted speed brakes through the F2H-3/4 Banshees.


 On the F3H Demon, however, the speed brakes were relocated to the more common position, either side of the aft fuselage, probably dictated by the different airflow on a swept wing.

Speed reduction was considered particularly necessary when Vought began testing the F7U-1 Cutlass that was capable of breaking the sound barrier in a dive. The problem was that if its single hydraulic system failed for any reason, the control loads became very heavy, increasing with speed. As a result, in addition to the split speed brakes on the inboard trailing edge of the wing, another pair of speed brakes was added under the engine inlets to slow the Cutlass down as quickly as possible so the pilot could regain control.

The extra pair of speed brakes was unnecessary on the F7U-3 since it had a fail-operate flight control system.

Sometimes the aft fuselage lacked a suitable surface for the location of speed brakes. The Douglas F4D Skyray had four small ones, mounted above and below the fillet inboard of the wing.

McDonnell placed the F4H's speed brakes on the bottom of the wing, sandwiched in between the main landing gear wheel well, the trailing edge flap, and the aft Sparrows:


Sometimes it took the engineers more than one attempt at locating the speed brakes. For example, this was the F8U mock up (note that the cannons are located directly under the forward fuselage);

On second thought, they made it a single panel on the belly aft of the nose wheel well and moved the cannons to the side of the forward fuselage.

While this meant that the F8U couldn't be landed with the speed brake extended, the primary reason for that was to add drag on approach so the engine response from the higher thrust required was quicker. Raising the wing for landing provided more than enough drag for that purpose.

The General Dynamics F-111 speed brake doubled as the forward main landing gear door:

The pilot had to bear in mind the increase in drag while the gear was being retracted.

On the F-14, Grumman located the speed brakes on the upper and lower surface of the aft fuselage between the engine nacelles, a single brake above and two below—also see http://www.anft.net/f-14/f14-detail-speedbrake.htm

On the F-18A/B/C/D, McDonnell provided a single speed brake on the top of the aft fuselage that doubled as a billboard.

The Navy determined that some of its jet attack airplanes needed more (and in one case less) speed brake than originally provided.

The North American FJ-4 was repurposed to be a backup to the Douglas A4D. Among other detail changes for the mission, an extra pair of speed brakes was added under the aft fuselage.

The Navy also decided that the original pair of A-6 speed brakes mounted aft of the engines were inadequate so Grumman added a pair of split panels to the trailing edge of the wing tip.

Ironically, it was subsequently decided after some service use that the fuselage-mounted brakes were a problem and the wing-tip ones were adequate, so the former were deleted in production and made inoperable on existing A-6s.

The Vought A-7, originally dubbed the Attack Crusader, was provided with a somewhat bigger speed brake for its strike mission capability;

Although it did not have the raised wing for added drag on approach and extended even farther down than the F8U's, the low-bypass fan engine was presumably deemed to be responsive enough at approach thrust, not to mention the drag of the multiple pylons on the wing.

The North American A3J Vigilante prototypes were built with an enormous speed brake under the fuselage.

However, the Navy decided to delete it for production. The speed brake function was instead provided by the lateral control system, which consisted of deflectors and spoilers on the wings. Instead of them extending asymmetrically for roll control, they all extended at the same time for speed reduction.

The Douglas A3D Skywarrior was also utilized for "dive" bombing, but what looks like a speed brake in front of the bomb bay was actually a spoiler that extended along with the bomb bay doors to eliminate the recirculation of air inside the bomb bay. Otherwise, the bombs would rattle around in the bomb bay after being released instead of dropping out.

The ultimate in speed brakes, however, is similar to the A3J/RA-5C's in that there is no dedicated speed brake per se, but much more effective. The F-18E/F's fly-by-wire flight control system permits speed control without speed brakes by utilizing the existing flight control surfaces, flaps, and the leading edge extension spoilers to add drag when desired. (Note that the flight control system is also programmed to toe-in both rudders for takeoff and approach for lower nose wheel liftoff speed and improved longitudinal stability respectively.)

The leading edge extension (LEX) spoiler had been added to disrupt the LEX-generated vortex that allows for controlled flight at very high angles of attack. When the pilot adds sufficient forward stick at a high angle of attack, the spoilers extend to disrupt the vortex, which results in a faster nose-down response.

Saturday, July 31, 2021

Carrier Landing: Inflight versus Free-flight Engagements

2 August: Well, this is embarrassing. I inadvertently reversed the designations of Inflight and Free-Flight. Thanks to Oscar Meyer for the correction.

If you're unfamiliar with the function of the tailhook in carrier landings, I suggest you look at this blog post first: https://thanlont.blogspot.com/2011/12/brief-history-of-tailhook-design.html

While "Inflight" and "Free-flight" would seem to be very similar if not identical conditions, as terms of art in carrier aviation, they are very different although separated by a very fine line. For one thing, both occur when the airplane's tailhook picks up an arresting cable (Cross Deck Pendant or CDP, another term of art) before the landing gear touches the deck. The critical difference is the airplane's vertical velocity at that moment: in an free-flight engagement, it is negative (a descent) or zero; in a inflight engagement, it is positive (climbing).

Free-flight engagements are not uncommon and generally benign. They often occur simply because the hook point is almost always below the main landing gear wheels as the airplane approaches the deck and the hook point is not very far from picking up a CDP when it meets the deck: https://www.youtube.com/watch?v=AvqNyf4E0M8

The F-35C hook point location relative to the wheels with the airplane about to touch down is an exception, but it still looks like an free-flight engagement might sometimes result:

 

Note the location of the tailhook on this TBM relative to the main landing gear as the LSO gives its pilot the cut, which will result in the Avenger sinking relatively steeply to the deck:

Both the flat approach to a cut that was used before the flight deck became angled and the descending approach guided by the visual landing system used thereafter reduced the likelihood of an free-flight engagement because of the steepness of the descent combined with wind over deck resulted in the hook point being on the deck for a relatively short distance before the main gear touched down. But they occurred:


A inflight engagement, on the other hand, is likely to result in significant damage. It is usually caused when the pilot tries to salvage a bad approach with an aggressive addition of power and/or aft stick:

Some have suggested that this Corsair had simply bounced, given its early reputation for doing so. I think not. One possibility is that the pilot decided to initiate a wave off after being cut by the LSO, which was verboten. In any event, the outcome was almost certainly very hard on the airplane.

This looks more like a bounce but it's hard to be certain without seeing earlier pictures of this particular landing.


An SU-33 aborted landing to a Russian carrier could have resulted in one of the worst inflight engagements of all time:


Click HERE for the video.

Wednesday, June 10, 2020

F8U-3 Monograph - Last Chance

A big part of the McDonnell F4H-1 story is the fly off with Vought's F8U-3, the best airplane that the Navy didn't buy, according to George Spangenberg, the Director of BuAer's Evaluation Division at the time. Steve Ginter is down to his last box of my F8U-3 monograph that provides much more information and background on that program than I could include in my F4H-1 monograph. For the whole story, I recommend that you include both in your library.


If you do buy one or both, I suggest that you do so directly from Steve so he gets the full value of the sale:

For the F8U-3, see http://www.ginterbooks.com/NAVAL/NF87.htm

For the F4H-1, see http://www.ginterbooks.com/NAVAL/NF108.htm

Friday, March 13, 2020

U.S. Navy 1950s Light-Attack Jet Programs

By January 1952, nuclear weapons light enough to be carried by tactical fighters and bombers had been qualified and were being stockpiled.
The Mk 7 was an implosion-type device, which meant it was relatively large in diameter. The Mk 8 was a gun-type device, smaller but much heavier, of interest to the Navy because it could withstand the shock of hitting the ground or water at a high incidence angle and speed, making it effective against submarine pens and ships/submarines. The subsequent improvements were the Mk 11, replacing the Mk 8, and the Mk 12, which was notably lighter and smaller than the Mk 7.

The Navy's carrier-based candidates for the new bombs were the Douglas AD-4B Skyraider and the McDonnell F2H-2B Banshee, with the B suffix standing for the armament changes necessary to carry, arm, and drop the Mk 7 and Mk 8. While modifications to Skyraider were relatively minimal, the -2B required a larger strengthened pylon, inflight refueling capability, and landing gear modifications to increase the ground clearance in order to taxi and takeoff with the Mk 7 even with a retractable fin.

F2H-2B side numbers 103 and 107 have inflight refueling probes and the requisite pylon under the inboard section of the left wing.

The AD-6 did not require a B suffix because it came off the production line with the nuclear-strike capability. In this case, one is carrying a Mk 8 on the center line station and two 300-gallon tanks that preceded the Douglas-designed "high-speed" external tanks and bombs.
Although white in gray-scale photos usually indicate florescent paint, it's possible that in the photo above it is in fact white paint in order to minimize the effect of the temperature spike from the bomb's detonation on the thinner skins of the control surfaces.

The AD had excellent range (a combat radius of almost 900 nautical miles) but a cruise speed of only 163 knots, which means a maximum range mission required 13 hours or more in the saddle. The F2H-2B had equivalent range with inflight refueling and a cruise speed more than twice that, 411 knots. The other shortcoming of the Skyraider was that it could only accelerate to a speed of 270 knots on the run-in to the target and for egress, which meant that being hoist by its own petard was a real possibility. The Banshee, even with its straight wing, could reach 500 knots, which means it could throw the bomb farther and be miles more away when it detonated.

While the Navy continued to assign the Skyraider to prospective nuclear-strike missions, it was clear that jets were to be preferred. The Bureau of Aeronautics (BuAer) considered several options, deploying five different ones in the 1950s in addition to the F2H-2B.
The McDonnell F2H-3/4 benefited from the -2B experience and all were delivered as nuclear-delivery capable so the B suffix was not required.
Note that the Mk 7 tail cone is rotated slightly counter-clockwise and the landing gear struts are pressurized to provide minimal ground and airframe clearance during taxi and launch.

In the meantime, the Navy's Bureau of Aeronautics contracted with Douglas, sole source, for the diminutive A4D-1 Skyhawk, a bespoke design optimized for the Mk 7-delivery mission. This early A4D-1 has a VHF navigation pod in place of the Mk 7 that dictated the long landing gear.

The F7U-3 was qualified to deliver nuclear weapons and deployed with several VF and VA squadrons. In parallel with the A4D program, the Navy contracted with Vought for an attack derivative of the Cutlass, the A2U.
However, the A2U-1 was cancelled based on the development problems with the Westinghouse J46 engine and the availability of another, less expensive option from North American, the FJ-4B.

The transonic FJ-4 had been procured as a day fighter but the supersonic Vought F8U Crusader resulted in it being delivered exclusively to Marine Corps fighter squadrons. However, it was well thought of and therefore an ideal candidate for the strike mission when modified with extra stores stations, controls for the nuclear weapon, and an additional pair of speed brakes. The result was the FJ-4B.

In the above display, a Mk 7 was loaded on the left pylon outboard of the refueling probe.

To fill the need for jets in attack squadrons before the A4D-1 and FJ-4B became available, BuAer procured the swept-wing F9F-8 Cougar as the F9F-8B beginning in 1954. This was possible at that point because the smaller Mk 12 was now qualified and provided adequate ground clearance with all four of its fins folded.


Nevertheless, none of the Navy's single engine nuclear-strike airplanes then available were all-weather capable. The Douglas F3D-2 night fighter was evaluated to fulfill that requirement but proved inadequate for other reasons.

Although the McDonnell F3H Demon, like the F7U-3, was intended to be a general purpose fighter with nuclear-strike capability, it doesn't appear to have been operationally assigned that role.

In early 1954, North American Aviation submitted an unsolicited proposal to BuAer for its NAGPAW, a single-seat, transonic airplane powered by two afterburning J46 engines that addressed the all-weather capability shortfall. The North American General Purpose Attack Weapon incorporated one of the first inertial navigation systems, an early stealth feature because it emitted no electronic signal betraying the airplane's presence (it was equipped with a small radar that could be used briefly and intermittently to update its position with respect to radar-significant ground features). Another unique design concept was the linear bomb bay. Conventional bomb bays eliminated the drag of the stores but were sometimes reluctant to allow the stores to drop out on release due to turbulence within the cavity. The linear bomb bay allowed the bomb to be positively expelled out the rear of the airplane along with empty fuel tanks.
The BuAer was interested but added requirements, e.g. a second crewman, zero wind-over-deck launch, and Mach 2 performance. The eventual result was the much bigger and faster A3J Vigilante. For more on NAGPAW, see https://tailhooktopics.blogspot.com/2020/03/north-american-general-purpose-attack.html

By the early 1960s all of the Navy's light-attack jets except for the A4D Skyhawk had been retired. Already the lowest cost, both procurement and operating, of the alternatives, it had been upgraded early during its long production run to include an all-weather capability. For more, see the revised edition of my book on the Scooter, published by Crecy and also available from Amazon: http://www.crecy.co.uk/scooter-the-douglas-a-4-skyhawk-story



Saturday, September 28, 2019

Angelo Romano's USN Electronic Aggressors Parts 1 and 2

Angelo sent me copies of his latest monographs a couple of months ago. They are so impressive and comprehensive that my words failed me when I sat down to review them. Fortunately, there have been more timely laudatory reviews on Amazon, Facebook, and other websites like Detail & Scale. For the latter, with a detailed synopsis of what is in the books, click HERE for Part One, and HERE for Part Two.

The short version is that Part One covers 1949 to 1977, beginning with the formation of the second Composite Squadron Thirty-Three for ASW duty and its subsequent designation and mission assignment changes up through 1970 when VAW-33 was assigned to the newly formed Fleet Electronic Warfare Support Group. It was now to provide a realistic electronic warfare environment during fleet exercises, functioning as an adversary.  The history continues up through 1977 with hundreds of pictures (most in color) of the airplane types used, first hand accounts, illustrations of ECM equipment, etc.

Part Two covers 1978 to 2000, continuing the history of VAQ-33 and the establishment of VAQ-34 in 1983 to accommodate the increasing demand for electronic warfare training. It's equal in size, coverage, and quality to Part One.

"Fight as you train, train as you fight" These squadrons are the equivalent of Topgun and its Naval Strike and Air Warfare Center successor in at-sea exercises to ready the crews of warships for combat and maintain their proficiency, including the realistic simulation of an anti-ship missile attack in a full-scale jamming environment. It's a little known but extremely important part of mission readiness.

While these books are available from Amazon and other sources, I recommend that you order them directly from Steve Ginter: Part One and Part Two.

Thursday, September 12, 2019

F8U-3 vs F4H-1 Dogfights at Patuxent River?

Often when the subject of the Vought F8U-3 comes up on the internet, someone posts something like "Crusader 3 test pilots would often jump the Navy pilots flying the F4H out of Pax River and get the better of them. Then the Navy brass complained and that was the end of the mock dogfights".

That scenario doesn't seem very likely. It is true that NASA Langley in Virginia was bailed the two F8U-3 prototypes for sonic boom studies after the Vought program was canceled. One arrived on 26 May 1959 and the other a month later (the latter was primarily used for spares). Flight tests were accomplished through October 1959 (I don't know the date of the last flight) and both airplanes stricken a month later.
 Langley didn't even bother adding the NASA logo on the tail of its F8U-3s during the five months they were on flight status there.

It is also true that there were F4Hs at Pax River during that time, No. 6 from 27 July to 13 August 1959 for NPE II, initial carrier suitability evaluation, and No. 3 in October, also likely for a couple of weeks, for NPE III, autopilot and air-to-air refueling evaluation. And Pax River and NASA Langley are not all that far apart.

However, No. 6 probably didn't leave the NAS Patuxent traffic pattern much, if at all, except on the ferry flight from St. Louis and the one to return.

I don't know whether there was any overlap between No. 3's visit to Pax in October and NASA's F8U-3 flight status; it's likely that there was and possible that they did tangle at least once.
Note that this picture was probably taken at a later date since No. 3 has a boilerplate IFR probe configuration being evaluated for production.

However, NASA test pilot Donald Mallick flew some of the Langley F8U-3 flights as described in his autobiography (a pdf can be downloaded for free from this NASA website: www.nasa.gov/centers/dryden/history/Publications/index.html).
I'm pretty sure that if there was such an encounter, he would have mentioned it.

In any event, given the relatively brief periods of overlap of the two types in the area and the intensive and controlled nature of the flight-test programs involved, it seems very unlikely that there was much opportunity for mock dogfighting. One of the two pilots would have had to have enough fuel after completing the test points on his flight card to go looking to bounce another fighter in his vicinity that turned out to be an F8U-3/F4H  that happened to be airborne at the same time.